Pumps of the air displacement type



y 1960 F. w. MCCOMBIE 2,943,578

PUMPS OF THE AIR DISPLACEMENT TYPE Filed Dec. 10, 195'? 2 Sheets-Sheet 13 F I G. 1

Inventor @wE /cw 4/ M (2/15 1 I At r e July 1950 F. w. MGCOMBIE2,943,578

PUMPS OF-THE AIR DISPLACEMENT TYPE Filed Dec. 10, 1957 2 Sheets-Sheet 2Inventor FreevEp/cw M da/v 1;

Atto ey in the chamber by means of floats.

United States: Patent PUMPS or THE AIR DISPLACEMENT TYPE FrederickWalter McCombie, London, England, asslgnor to Megator Pumps andCompressors Limited, London, England Filed Dec. 10, 1957, Ser. No.701,768

Claims priority, application Great Britain Dec. 13,1956

2 Claims. (Cl. 103-242) This invention relates to pumps of theair-displacement type, ie to pumps wherein the liquid, often a liquidwhich is diflicult to handle with ordinary pumps, is displaced by air orother gaseous medium hereinafter referred to as air for convenience ofdescription.

Such pumps include a chamber having inlet and outlet valves near thebottom and a connection at the top through which air can be evacuated todraw the liquid into the chamber and admitted under pressure to forcethe liquid out of the chamber. u

It is present practice to control the evacuation and admission of air inaccordance with the level of the liquid Such floats are generallyunreliable in operation as they are subject to sticking, corrosion andincrustation.

The chief object of this invention is to evolve a generally improvedconstruction of air-displacement type pump which does not rely on suchfloats for its successful operation.

A pump of the air-displacement type is characterized in accordance withpresent invention in that the chamber is movable in a vertical directionin accordance with the weight of the contained liquid, thereby actuatingthe valve controlling the evacuation and admission of air to the chamberdirectly or indirectly.

The weight of the empty chamber is balanced by a counterweight or springso'that the chamber rises as it empties and falls as it fills.

Consequently, the terminal movement of the chamber in an upwarddirection may be arranged to open the air valve controlling evacuationof the chamber and thus allow the chamber to fill with liquid andcommence to fall, the terminal movement of the chamber in a downwarddirection being used to open the valve admitting air under pressure toexpel the liquid.

it will be appreciated that the air valves may be actuated by themovement of the chamber through mechanical means, or indirectly throughlimit switches or pilot valves.

The air connection tothe chamber may be made by a further tube or pipewhich again may be of a flexible character, or may be otherwise arrangedto allow unrestricted movement of the chamber in a vertical direction.

Referring to the drawings:

Figures 1 and 2 are diagrammatic views illustrating the construction ofan air-displacement type pump in accordance with the invention; and

Figures 3 and 4 are fragmentary views illustrating two modifications.

Referring in the first case to Figures 1 and 2, the pump comprises afixed casing 1 having inlet and outlet connections 2 and 3 at itsopposite ends and a further connection 4 at an intermediate point. Theflow of liquid through the fixed casing is under the control of inletand outlet non-return valves 5 and 6, these valves normally maintaininga closed position under the action of gravity.

2,943,578 Patented July 5, 1960 A flexible pipe 7 is connected withoutlet connection 4, this pipe 7 leading to a chamber 8 which ispivotally connected at 9 to a steelyard 10 having a fulcrum point 11 andcarrying an adjustable weight 12 which wholly or partly balances theweight of chamber 8. A spring may be used instead of or in addition toweight 12.

The free end of the steelyard 10 is pivotally connected at 13 to a link14 which in turn is pivotally connected at 15 to a lever 16 associatedwith a three-way valve mounted in a valve casing 17.

The lever 16 has associated with it an upstanding lever 18 carrying aweight 19.

A pipe connection 20 is taken from the valve casing 17 to a connection21 on the upper end of the chamber 8, the pipe 20 terminating in aflexible pipe 22 which is itself connected with the part 21.

The valve casing 17 has a connection 23 for the entry of air underpressure and a further connection 24 to atmosphere or vacuum.

In the construction shown in Figures 1 and 2, liquid can enter the fixedcasing 1 via the inlet connection 2 and displace valve 5 into theposition shown, the connection 4, flexible pipe 7 and chamber 8 thenfilling with liquid, the air being displaced from chamber 8 as a resultof pipe 20 being connected to atmosphere or vacuum through the medium ofthe three-way valve. When a sufiieient weight of liquid has enteredchamber 8, chamber 8 will move downwardly under the weight of. thecontained liquid and against the action of the weight 12, andconsequently lever 18 together with its weight 19 will be moved over adead centre position into the position shown in Figure 2. The pipe 20and the interior of chamber 8 will then be connected with a source ofcompressed air supply through the medium of the three-way valve whichhas moved through an angle of and consequently the liquid contained inchamber 8 and its associated flexible pipe 7 and connection 4 will bedisplaced downwardly, causing valve 5 to close and valve 6 to open, andwill so be discharged from the outlet connection 3. Owing to thereduction of weight resulting from the discharge of the liquid fromchamber 8 and pipe 7, the chamber will now rise and operate the three-'way valve, so that the pipe 20 is again connected to the atmosphere orvacuum and the cycle repeated.

Although a rotating three-way valve is shown by way of example, anysuitable kind of valve may be used.

As shown in Figures 1 and 2, the chamber 8 is of cylindrical form and isconnected with the fixed casing through the medium of a flexible pipe 7.It may be desirable in'some cases to avoid the use of this cylindricalchamber 8, in which case the necessary weight of liquid can be entirelycontained in a long pipe bent or folded back on itself or Wound in acoil or helix as shown in Figure 3. The helical pipe 25 is closed at itsupper end by a closure member 26 which in turn is pivotally connected at9 with the steelyard '10. It will be seen that the lower end of the pipe25 is connected directly with connection '4 associated with the fixedcasing.

Such an arrangement is simple to make and easy to flush out for cleaningand has the advantage that the pipe 25 ban be comparatively long, thusgiving great flexibility and also enabling a considerable volume ofliquid to be contained in its convolutions.

The steelyard 10 again carries a Weight 12 by means of which the weightof the helical pipe is partly balanced, the free end of the steelyardbeing connected with the three-way valve through the medium of a link 14as in the previously described arrangement.

It will be seen from Figures 1, 2 and 3 that the pipe 7 or 25, where itjoins connection '4, lies substantially horizontally, thus avoiding anymaterial vertical re- 3 action :on the pipe arising-.:.fromthe pressureof tl'ie'liquid whichwwould make .the .workingof the, mechanism vary.with every variation of pressure or vacuum, instead of being controlledentirely by the weight of liquid in the pipe: 1 The pipepreferablyhas,however, :23. sligh'tslope 5 downwards towards: the:,:connection '4 tofacilitate) drainage.

It will be appreciatedathatiin the-.previouslywdescribed, 1 constructionillustratediby Figuressl andt2, thezpipe Jis necessarilyiof aflexiblel'charactenas in order to operatezlfl the valve direct, ;the:chambenr8 must-ahave asubstantial movement in avertical;;direction.;..:

The .carrangernent; shownF-in Figure-s4 has,ztherefore,:1, been designedto permit of satisfactory operation WithLfiL, pipe ,7. composedof amore;.rigid:material;such-,as metal 15 or glass. Such a pipe composed ofamorerigiimaterialti will;,;-if correctly .designed,1-be incapable :of.a small degree of longitudinal flexure which will be :sufficienhtoinitiate; the operation .of a .suitablesvalve. 1

In such a case, the steelyardlO again .carries;al balancet.;20

weight-.12 and is also.-.conne.cted.-with a fixed.;p.oint,.by

means ,of a coilsspringr27landgan adjusting 'device'28,'1;i whereby thebalance of the chamber, 2 can-.i-be-accuratelyn-t determined.

In ,this constructiomhowever, :instead of operating 1116 :26

valve dire'ct,.theivalve is electrically actuatedqandacomal prises-asolenoid operated three-way valve29,;theiwind1 ingslof thesolenoid,being.:com1ected:by leads 30 witha pairnof micro switches'31and 32,,arrangedon'opposite.:. SldBSzOf the steelyard. Atleastoneof themicro switches..z 31 and :32 maylbe'adjustable, verticallyhbyimeansuofa. finger-actuated.adjusting nut-=33 ;associated:with 'a. fixed..-:

paruof the apparatus:

With; this ::arrangement,:,.by suitable; adjustment of .the,.-..:adjusting-devices '28 and 33,;the .valve 29v canbeoperatede3 with only-aminimum of upward-:and .downwardmover ment-cof :thei'chamberx 8and.1ongitudinal:.flexure;;of

It will benotedthatthe .weightsi-12andh19 and them springx27 whichbalance the .weightyofthe chamber. andr liquid are adjustableso as tocompensatefor the. 1ifI'e1' v ing-specificr gravities of different:liquids .that. maybe pumped. These adjustments'may alsoflbe used, incases .-1 where .it is desired '10 cleanse. the:pump completelyvafter,-.. usegbypumpinga eleansingliquid through it, sothat;1 the:cleansingliquidis made ,to rise :slightlyhigherzin then:

chamber: than .thepumped liquid,

'lhe'pipe' 7 or 25 -may be'composed of metal; glass, rubben orothensuitablematerial .andimayv with advantage be partly or whollytransparent, thus enabling the level of liquid within the pipe to beobserved. For example, pipes 7 and 25 may be composed of a transparentor substantially transparent thermo=plastic material such as, forexample, polyethylene, methyl methacrylate, polyvinylch1oride,i'nylon:ortether: suitable material;

I claim:

1. A pump'of .the'f 'airdisplacement type'icomprising ahelicaltithedefinir'rg a chamber, the lower end of .said tube being fixed, saidtube being flexible with the'upper end thereof being' movable inaceordancewithrthe weight of a liquid containedewithin the, coilsthereof, a pipe in communication" with theupper'end of said tubeforevacuating air therefromj-iand'iadmittingzair thereinto, a valveconnected to said pipe and controlling the evacuation and admission ofair to the chamber, means operativelyzxonnectechiwith lthe'zuppenzend-zof ;said,.;tube .for

controlling saidwalve-to evacuate; airswhenisaidiend is inthe-.rupperspositionrandn-admittainwhendt is in a lower e position; and:liquidsconnectiommeans: :in communication.

with the lower 'z-endmf :saidi'etubene,

2. The'rpumpzof rclairm'zl whereintsaid'.;tube..1is constructedteof athermoplastic imaterial,:;said:.;valve. con-.7trolling:means,including'eounterbalaneingmeans:attached to the; 'upper:endzof saiditube fonraising itzupon removalv of the liquid therefrom.

References: (lit'ed'rin the .file .of this patent UNITED -.STAIESIPATENTS I

